How to Diagnose and Treat Dog Diarrhea

Four Methods:Determining If a Diagnosis is NeededGetting Your Diagnosed by a VeterinarianTreating Uncomplicated DiarrheaTreating Complex Diarrhea

When your dog has diarrhea you want him better—fast! Indeed, there is no better motivator for seeking treatment than diarrhea on the lounge room carpet. One of the most common reasons for doggy diarrhea is your dog eating something he shouldn’t, and which upsets his tummy. However, sometimes the reason for the diarrhea isn't as obvious and a work-up needs to be done.

Method 1
Determining If a Diagnosis is Needed

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    Consider your dog’s overall health, apart from the diarrhea. If your dog is well apart from the diarrhea, and has recently eaten something decidedly dodgy, then blood tests and fecal analysis may be a waste of both your time and money. Some dogs have a stronger constitution than others and can cope with eating an old burger in the trash, or that extra tasty fox poo, whilst others will get diarrhea.
    • Be extra vigilant if table scraps are likely to upset his tummy, and maybe even muzzle your dog on walks if he scavenges from bins or eats animal feces.
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    Try minimizing your dog’s diet for 24 hours before you bring him to the vet. Do not feed your dog for 24 hours. After this period of time, reintroduce a very bland diet (such as boiled chicken and rice). Doing this may help to settle your dog’s stomach, and eliminates the need to go to the vet.
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    Know when to bring your dog to the vet. As a rule of thumb, if the diarrhea persists despite starvation, or your dog is lethargic, off his food, vomiting, or otherwise unwell, then it is a good idea to seek a veterinarian's advice.
    • Based on his or her physical exam of the dog, the vet will then decide if tests are necessary, or if there is sufficient evidence just to start treatment to help your dog get over his tummy upset.
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    Get a specific diagnosis if your dog is sick, in addition to his having diarrhea. Those cases where a specific diagnosis is most helpful are those dogs with persistent diarrhea, which is described as lasting more than four to five days. Other signs that you should get a specific diagnosis include:
    • Your dog loses weight.
    • Your dog does not respond to treatment, starvation, or a bland diet.
    • You have a puppy with persistent diarrhea (they are more likely to have an infection or parasites, so identifying a specific bug helps target treatment).

Method 2
Getting Your Diagnosed by a Veterinarian

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    Tell your vet your dog’s history. In this context the "history" refers to relevant information about your dog, such as the dog's vaccination status (vaccines protect against some of the viral causes of diarrhea), recent diet, and the animals he has been mixing with.
    • The other side of your dog’s history is a detailed description of what the diarrhea looks like and how often your dog moves his bowel. This information helps the vet to pinpoint whereabouts in the gut the diarrhea originates from.
    • For example, a dog that spends a lot of time repeatedly straining may have large bowel diarrhea, while a dog that goes infrequently but then "explodes" is likely to have small bowel diarrhea. This is not just of academic interest, because the veterinarian will immediately start drawing up a mental list of different conditions that cause either large or small bowel diarrhea.
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    Collect a fecal specimen for your vet. If your dog has already had treatment but failed to respond, or has long term diarrhea (2 weeks or more) prior to being taken to the vet, then it is likely the vet will want to send a fecal specimen to the lab. The vet supplies you with a fecal specimen pot that comes with a handy scoop attached to the underside of the lid. Go home and collect your dog's next fecal offering. To do this[1]:
    • Simply scoop a small volume of feces up with the collecting spoon and pop it in the pot, then screw the lid back on. You don't need much; less than a teaspoon of feces should suffice.
    • Store the pot somewhere away from food, perhaps put it in a plastic bag and leave it in the garage or shed, until you need it the next day. Always wash your hands well afterwards.
    • The fecal specimen is usually "pooled". This means that three samples (from the same dog) are taken over three consecutive days and put in the same pot for analysis. This increases the likelihood of finding any infectious agents. The pooling is necessary because the microorganisms might not be passed each time the dog has a bowel movement. By collecting more than one sample over a few days, the chances of missing an infectious organism are reduced.
    • At the lab the technician examines the sample under the microscope to look for parasitic eggs and larvae, and the presence of coccidian parasites. In addition to this, some of the feces are cultured, to encourage growth of any pathogens such as salmonella or campylobacter.
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    Schedule your dog for a blood test. If your vet thinks that the diarrhea may be caused by an underlying medical condition, he or she will want to do a blood test for your dog. Some of the medical conditions that the vet will look for include liver disease or pancreatitis.[2]
    • These blood tests look at organ function and the balance of red and white cells in the body. This gives information about organ health, protein levels, anemia, and signs of infection. In turn these results may suggest a more specific line of investigation that is necessary to diagnose a problem for which diarrhea is merely a symptom.
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    Schedule a bowel function blood test for your dog. This test is usually saved for last, and will only be scheduled if the fecal analysis and blood tests come back normal or negative, but the diarrhea persists. These tests look at the amount of pancreatic enzymes (to diagnose Exocrine Pancreatic Insufficiency, which causes diarrhea), a lack of cobalamin in the bowel wall (this is a B vitamin that is required for efficient absorption of nutrients), and if an overgrowth of unhelpful bacteria have colonized the gut. Each of these, when imbalanced can cause diarrhea.[3]
    • The vet will also suggest these tests if your dog is losing weight rapidly, despite treatment.
    • The vet may skip straight to these tests if your dog’s medical history suggests that he may lack pancreatic enzymes.
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    Get imaging done. Imaging includes radiography and ultrasound. Imaging tends to be reserved for dogs that are losing weight and still have diarrhea, but all of the other tests listed above have come back normal.
    • Imaging allows the vet to take a look at the bowel and see if it looks normal. In particular, this can help to rule out bowel inflammation and cancer.
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    Have your dog’s bowel biopsied as a last resort. A bowel biopsy is invasive, and has a high complication rate, so it is generally avoided when possible. A biopsy involves a laparotomy (going into the dog's abdomen) and removing slivers of bowel wall to be sent for histology. The problem with having a biopsy done is that because the samples are taken from diseased tissue, the risk of sutures slipping is increased, which could result in bowel contents leaking into the abdomen, with potentially life threatening consequences.
    • Your clinician will discuss the risks, but bowel biopsy is a procedure of last resort and it may well be worth using information from previous tests to decide on a "educated guess" treatment (diagnosis by treatment), before resorting to biopsy.
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    Diagnosis the condition through treatment. There are certain conditions, of which inflammatory bowel disease is one, that do not show up on the tests listed. This is because inflammation of the bowel wall inhibits proper digestion resulting in diarrhea.
    • If all the test results come back negative then the vet may suggest a trial therapy for inflammatory bowel disease, before resorting to bowel biopsy. If your dog responds to treatment, then you will have avoided needing a biopsy. If not, then taking that extra step is warranted.

Method 3
Treating Uncomplicated Diarrhea

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    Define uncomplicated diarrhea. Many dogs have a tummy upset but are not sick in any other way. This means that while they have diarrhea, they are otherwise cheerful and energetic (ie. they are acting like their regular selves).
    • For these dogs simple tactics such as withholding food and then re-introducing a bland diet may be all that is needed. These tactics are listed in the following steps.
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    Keep your dog from eating for 24 hours. While you should keep your dog from eating, you should give your dog access to fresh drinking water during this time. Starvation may help because when food sits in your dog’s stomach, it stimulates the contraction of muscles in your dog’s gut, which makes the bowels overactive, and could lead to diarrhea.
    • By resting the gut, it keeps the bowel’s activity to a minimum, which will allow it to return to normal.
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    Feed your dog a bland diet after 24 hours. Rich foods and high fat diets are harder to digest than bland food. Once your dog has been starved, stick to bland, easy to digest food when you start feeding your dog again. Bland foods include white meat (chicken, turkey, rabbit, or cod) and boiled white rice or pasta.
    • An alternative idea is to feed your dog a prescription diet such as Hills ID or Purina EN that are gentle on the bowel and speed up recovery time.
    • Continue feeding your dog this bland diet until your dog forms regular stools. Continue to feed him this bland diet for two to three days, and then gradually begin to add in his regular diet.
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    Give your dog probiotics.Diarrhea physically expels the bacteria in the bowel that help your dog digest food. To speed up recovery it helps to give a dietary supplement of helpful bacteria, to colonize the bowel and get your dog’s digestive system back on track. Dogs, however, use different digestive bacteria than people do, so there is no point feeding your dog a human probiotic product.
    • There are many canine probiotics available without prescription from your veterinary clinic, such as Promax (an oral paste) or Fortiflora (granules which are added to food). Typically these are given once a day for three days.

Method 4
Treating Complex Diarrhea

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    Define complex diarrhea. If your dog’s diarrhea is the result of an infection or disease, rather than snacking on something he shouldn't, then medical treatment may be needed, in addition to strategies such as feeding him a bland diet and giving him probiotics.
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    Get wormers for your dog if your dog has worms. If the fecal analysis shows the presence of worms, then a good broad spectrum wormer is essential. These medications act by disrupting nerve transmission within the parasite, paralyzing it and causing it to be passed out in the feces.
    • Examples include wormers containing milbemycin or praziquantel (such as Milbemax or Drontal).
    • A single oral dose will get rid of the parasites present at that moment in time. It is wise to repeat the dose a month later. The dose is 0.5 mg of milbemycin per kg body weight, and so a 10 kg dog is given one standard sized milbemax tablet.[4]
    • If a coccidian infection is identified, the treatment is fenbendazole (Panacur). This works by inhibiting the formation of the coccidian cell wall system, causing it to die. Fenbendazole is given with food once a day for three to five days. The dose of panacur is 100 mg/kg per dose, so a 20 kg dog is given 24ml of the 10% solution by mouth, once a day.[5]
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    Get amoxycillin for your dog. Antibiotics are usually used to treat specific infections like salmonella, or campylobacter. The antibiotic of choice in most circumstances is the broad spectrum potentiated amoxycillin (eg. Synulox). This antibiotic works by destroying the bacteria cell wall.
    • Typically, the dose is 12.5 mg/kg twice a day. Thus a 20 kg dog would receive a 250 mg tablet twice a day. A 5 day course is usually sufficient.[6]
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    Get a different antibiotic if your dog is infected with campylobacter. An antibiotic from the trimethoprim sulphonamide family has better action against this bug than amoxycillin. This antibiotic prevents the campylobacter from metabolising, so it cannot reproduce.
    • A 10- 14 days course is usually required.The dose is one Trimacare 80 tablet, for every 16 kgs of body weight.[7]
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    Get oxytetracycline if bacterial overgrowth is present. In this case oxytetracycline is used as it selectively kills bacteria associated with overgrowth. This antibiotic prevents protein synthesis in these bacteria, which stops them from growing.
    • Again, a 14 day course may be necessary, to give the good gut bacteria a chance to fill the gap left by the pathogenic bacteria. The dose is around 20 mg/kg body weight, three times a day. Therefore, a 10kg dog is given a 100 mg tablet three times a day.[8]
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    Try putting your dog on a hypoallergenic diet. If a dietary allergy or food hypersensitivity is suspected, then removing the allergen from the diet will treat your dog’s diarrhea. Get a commercial prescription hypoallergenic diet for your dog.
    • Examples of these diets include Hills ZD or ZD Ultra, or Purina HA. Make sure your dog does not eat any other types of food while on these diets, or the hypoallergenic diets will not be effective.
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    Give your dog vitamin B injections. A dog with long term diarrhea will have depleted levels of cobalamin in his bowel wall. This creates a vicious circle because cobalamin (a B vitamin) is needed to aid digestion. The answer is to give four, weekly injections of B vitamins, in order to replenish your dog’s vitamin levels.
    • This treatment needs to be given by injection, because this B vitamin may be destroyed by gastric acid if given by mouth.
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    Get a prescription for steroids for your dog. For conditions such as inflammatory bowel disease, corticosteroids may be needed to get your dog healthy again. Steroids are potent anti-inflammatories that reduce swelling in the gut lining.
    • A typical dose is 2mg/kg for 2 weeks by mouth, given with or after food. After that the dose is reduced by half every 2 weeks, so as to slowly wean the dog off the steroids (a sudden withdrawal can trigger an Addisonian crisis where the dog collapses, and may even go into a coma).
    • Thus a 10 mg dog would take two 5 mg tablets, once a day for two weeks, then one 5 mg tablet for two weeks.

Sources and Citations

  1. Interpretation of Laboratory Results for Small Animal Clinicians. BM Bush. Publisher Wiley-Blackwell
  2. Interpretation of Laboratory Results for Small Animal Clinicians. BM Bush. Publisher Wiley-Blackwell
  3. Interpretation of Laboratory Results for Small Animal Clinicians. BM Bush. Publisher Wiley-Blackwell
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Article Info

Categories: Canine Health | Intestinal and Digestive Health